Dust-free hair bleach powders

ABSTRACT

The invention relates to substantially dust-free bleach powders that, when mixed with aqueous hydrogen peroxide, yield activated bleach compositions that exhibit improved thixotropy. The bleach powders comprise at least one de-dusting agent and at least one peroxygenated salt. The de-dusting agents, which are preferably present in an amount less than about 10% by weight of the bleach powder are inert, substantially hydrophilic compounds selected from alkylated esters, cyclic ethers and cyclic esters. The bleach powders also comprise powdered polytetrafluoroethylene (PTFE) in an amount of about 1-5% by weight of the bleach powder. The bleach powders also comprise an ammonia source, e.g., an ammonium halide, diammonium phosphate, ammonium sulfate and mixtures thereof. Optionally, one or more hair conditioning agents, thickeners and desiccants may be added to the dust-free bleach powder.

This application is a 371 of PCT/US96/13764, filed Aug. 27, 1996, whichis a continuation-in-part of application Ser. No. 521,192, filed Aug.30, 1995.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to substantially dust-free bleachingformulations. More specifically, the invention is directed tosubstantially dust-free hair bleaching powders comprising at least onede-dusting agent and at least one peroxygenated salt. The invention alsoprovides hair bleaching powders that, when mixed with aqueous hydrogenperoxide, yield an activated bleaching composition that can flow evenlythrough hair. More specifically, the bleaching powders of the inventionalso comprise powdered polytetrafluoroethylene (PTFE), which improvesthe viscosity and slip characteristics of the activated bleachingcomposition.

2. Background of the Invention

Conventional hair bleach powders are compositions which are used forlightening hair color. Typically, these products are sold to theconsumer as dry powders, which must be mixed with aqueous solutions ofhydrogen peroxide before they are used. Upon mixing, the components inthe bleach powder and the hydrogen peroxide solution form an activatedbleaching composition which is then applied to the hair. The activatedbleaching composition lightens the hair by oxidizing natural hairpigments, such as melanin.

Typical hair bleach powders contain a reactant which interacts withhydrogen peroxide to form oxygen, which breaks down melanin in hair.Commonly, such reactants include, inter alia, peroxygenated ammonium,sodium or potassium salts of persulfates, perborates, percarbonates andthe like.

It is usually necessary for adequate oxygen formation to have anactivated bleach composition with a pH in the range of 9.5-11.5 uponaddition of the hydrogen peroxide solution. The peroxide and thepersulfate are both acids, which are activated at a basic pH.Accordingly, it is common to add a base, such as an amine alkalicompound or a metasilicate, to hair bleach powders.

Conventional hair bleach powders may also contain other additivesincluding thickeners, such as hydroxy-alkylated cellulose, that helpform the powder base. Such bleach powders are also susceptible, uponstorage, to degradation resulting from atmospheric moisture. Thus, it isalso common to add desiccants, such as silica derivatives, to preventthe bleach powders from being degraded by moisture before use.

There are several disadvantages associated with conventional hair bleachpowders. Specifically, conventional bleach powders have a tendency toform dust during handling, transport and storage. Dusting also occursduring transfer of the bleach powder to the mixing chamber prior toadmixing with the aqueous solution of hydrogen peroxide. Moreover, thepersulfates and the alkaline silicate reactants are corrosive, and canbe dangerous to the handler. These dusts irritate the eyes, therespiratory canal and the mucous membranes. Ammonium persulfate is anespecially problematic irritant.

For these reasons, various attempts have been made to reduce the dustingcharacteristics of hair bleach powders. Partial success has beenachieved through the addition of substantially water insolublecompounds, such as oils or liquid waxes, to the bleach powder. Theseoils or waxes coat the individual powder particles and agglomerate theminto larger sized particles. Such bleach powders are thus renderedsubstantially dust-free due to their lack of small particles.

Published European Patent Application Publication No. 0583,767 A2, ("EP'767"), provides an example of this approach. EP '767 discloses a dryfree flowing, dust-free hair bleach powder, wherein a powder basecomprising ammonium, sodium and potassium persulfate salts is treatedwith "inert adsorbates" or inert liquids which include, inter alia,mineral oils, natural oils and fluorosilicone fluids.

These inert liquid additives, which are oils, are disclosed asperforming two functions: (1) as an adhesive to aggregate small powderparticles into particles having a size greater than 40μ and (2) as alubricant to coat the particles so they do not abrade and form dust.Therefore, the inert liquid additives function primarily as de-dustingagents.

In order to obtain the desired characteristics of the compositionstaught by EP '767, the inert liquid is said to comprise about 10-25% byweight of the hair bleach powder with the preferred range being about14-20% by weight.

U.S. Pat. No. 4,170,637 ("'637 patent") also recites a hair bleachcomposition which comprises an intimate mixture of particulatepersulfate salts and alkaline silicates dispersed in a hydrophobicorganic carrier, such as an oil or wax, present in an amount from about30-70% by weight of the total mixture. The resulting compositions arenot powders, but have a "paste to cream" consistency.

European Patent Publication No. 0,560,088 B1 ("EP '088") disclosesdust-free bleach powders that are also treated with oils and/or liquidwaxes. These ingredients comprise from 2.5 to 25%, and preferablybetween 8 and 12%, of the total weight of the bleach powder. The addedsubstances are also taught as being substantially water-insoluble("Industrie et technologie des Corps Gras" (Industry and Technology ofFatty Substances), Alton E. Bayley; "Romps Chemie Lexicon", Oho Albrechtand Neumuller; "Introduction to Fats and Oils Technology", Peter J. Wan;Larousse Dictionary). Specifically, EP '088 recites the use of paraffinoil and silicone oil, which are hydrophobic, water insoluble substances.

While the above-recited treatments produce substantially dust-freebleach powders, these powders still suffer from significant drawbacks,because they form unstable oil based emulsions upon mixture with theaqueous hydrogen peroxide. Therefore, to compensate for thisinstability, additional components, such as surfactants and emulsifiers(e.g., polyoxyethylenestearates or polypropyleneoxides), must be addedto the powder. Moreover, when bleach powders containing oil-basedde-dusting agents are mixed with aqueous hydrogen peroxide, they take along time to form a usable paste.

Another undesirable aspect of conventional bleaching compositions isthat they fail to exhibit satisfactory thixotropy characteristics. Anactivated bleaching composition with good thixotropy moves through thehair with little effort, but also remains in the location where it isapplied. In other words, good thixotropy properties help the bleachcomposition recover from sheer forces exerted on it during applicationto hair. Activated bleaching compositions prepared with theabove-mentioned prior art dust-free hair bleach powders do not exhibitgood thixotropy, but instead require excessive embrocation or wetting toeffectively and evenly bleach the hair. It is difficult to obtaindesired thixotropy for an activated bleaching composition, since amoderately low viscosity is required to impart the right amount ofspreadability. However, if the viscosity is too low, the prepared bleachpaste or cream will not stay in its applied location. Therefore, it iscritical for an activated bleaching composition to have an optimumviscosity to impart desirable aesthetic characteristics to the hair.

Conventional bleach powders have further disadvantages in that theydecompose under humid conditions and have relatively low ignitiontemperatures. Moreover, none of the conventional dust-free bleachingpowders incorporates substantially hydrophilic de-dusting agents, whichsimultaneously suppress formation of dust and impart improved thixotropycharacteristics to activated bleaching compositions made from thesepowders. Conventional bleach powders also do not incorporate powderedpolytetrafluoroethylene (PTFE), which prevents clumping of the powderwhen mixed with aqueous peroxide and improves viscosity and slipcharacteristics of the bleaching mixture.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a substantiallydust-free bleaching powder which can be used to prepare an activatedbleaching composition that overcomes the disadvantages of the prior art.

Another object of the invention is to provide a substantially dust-freebleaching powder which comprises a substantially hydrophilic de-dustingagent to enhance solubility of the bleach powder in an aqueous peroxidesolution.

It is a further object of the invention to provide substantiallydust-free bleaching powders that, when mixed with aqueous hydrogenperoxide, form activated bleaching compositions that have improvedthixotropy and slip characteristics.

Another object of the invention is to provide a substantially dust-freebleach powder that is less irritating to the user, in which an ammoniumhalide, ammonium sulfate and a non-ammonia peroxygenated salt aresubstituted for ammonium persulfate used in conventional.

A further object of the invention is to provide a substantiallydust-free bleach powder that incorporates powderedpolytetrafluoroethylene (PTFE) to improve the viscosity and slipcharacteristics of the activated bleaching compositions and to preventclumping of the powders when mixed with aqueous peroxide.

A still further object of the invention is to provide substantiallydust-free bleach powders having conditioning agents which improve theaesthetic feel of the hair.

It is a still another object of the invention to provide substantiallydust-free bleach powders that have retarded rates of decomposition underatmospheric humidity.

An additional further object of the invention is to providesubstantially dust-free bleaching powders that have high ignitiontemperatures.

These and other objects of the present invention are achieved by one ormore of the following features of the invention.

The objects of the present invention are accomplished through theinclusion of de-dusting agents, that are substantially hydrophiliccompounds, and powdered PTFE in the bleach powder. The de-dusting agentsare applied to a mixture of the peroxygenated salt and powderedPTFE-containing bleach powder, such that the de-dusting agent coats thebleach powder particles. Preferably, the application of the de-dustingagents is via spraying. This process produces a substantially dust-freebleach powder which can be mixed with an aqueous solution of a peroxide,such as hydrogen peroxide, to form an activated bleaching composition.

In a preferred embodiment of the present invention, the substantiallyhydrophilic de-dusting agents are cyclic ethers, alkylated diesters orcyclic esters. In a more preferred embodiment, the cyclic ether may be adialkyl cyclic ether, such as dimethyl isosorbide or diisopropylisosorbide. The alkylated diester may be an alkylated adipate, alkylatedsebecate or alkylated oxalate, wherein the alkyl groups have 3 to 6carbon atoms. Preferred alkylated diesters include diisopropyl adipate,diisopropyl sebecate, and diisopropyl oxalate. Preferably, the cyclicester is γ-butyrolactone.

In a further preferred embodiment, the de-dusting agent is present in anamount less than 10% by weight of the bleach powder, preferably 2 to 56and, more preferably, 2-3%.

The powdered PTFE is present in the bleach powder in an amount of about1-5% by weight, preferably 2-4% and more preferably about 3%.

In a still further embodiment of the present invention, theperoxygenated salt may be selected from among one or more of the saltsof persulfate, perborate, metasilicate, or percarbonate. Sodium andpotassium persulfate salts are preferred.

In other preferred embodiments of the invention, several additives suchas conditioners, bases, thickeners and desiccants may be added to thepowder.

Other features and advantages of the invention will be apparent from thefollowing description of the invention and from the claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a free flowing, substantially dust-freehair bleach powder that can be mixed with aqueous hydrogen peroxidewithout clumping to form an activated bleaching composition withimproved thixotropy.

The substantially dust-free bleach powders of the invention compriseparticles of one or more peroxygenated salts, that are coated with asubstantially hydrophilic de-dusting agent. The bleach powders of theinvention also comprise powdered polytetrafluoroethylene (PTFE). Thesubstantially dust-free bleach powder may also contain additionalcomponents including, inter alia, conditioners, bases, thickeners anddesiccants. Before they are used to bleach hair, the substantiallydust-free bleach powders must be combined with an aqueous peroxidesolution, especially hydrogen peroxide, which forms an activatedbleaching composition.

The invention is based, in part, on the finding that substantiallyhydrophilic cyclic ether compounds, especially dimethyl ethers, cyclicester compounds, and alkyl diesters are effective de-dusting agents forhair bleaching powders. The invention is further based on the surprisingability of bleaching powders comprising these substantially hydrophilicde-dusting agents to simultaneously suppress formation of dust andimpart superior thixotropy characteristics to bleaching compositionsmade from these powders. The invention is still further based on theimprovements to viscosity and slip characteristics of the bleachingpowders provided by the inclusion of powdered PTFE therein. The additionof PTFE also reduces clumping of the substantially dust-free bleachpowder upon mixing with aqueous peroxide.

Suitable peroxygenated salts for use in the bleaching powders of theinvention include salts of persulfate, perborate, metasilicate, orpercarbonate. Preferred peroxygenated salts include sodium and/orpotassium persulfate.

The de-dusting agents which may be incorporated in the dust-free bleachpowder include various substantially hydrophilic agents which enhancemiscibility of the powders with aqueous hydrogen peroxide solutions.Preferred de-dusting agents include cyclic ethers, cyclic esters andalkylated diesters. Preferred cyclic ethers include dialkyl cyclicethers, such as dimethyl isosorbide or diisopropyl isosorbide. Preferredcyclic esters include γ-butyrolactone. Preferred alkylated diestersinclude alkylated esters wherein the alkyl groups have three to sixcarbon atoms. More preferred alkylated diesters include dialkylsebecates, dialkyl oxalates, and dialkyl adipates. Most preferred arediisopropyl sebecate, diisopropyl oxalates and diisopropyl adipates.

The de-dusting agent comprises less than 10% by weight of the totalbleach powder. This ensures that the activated bleaching compositionmade using the powder does not have a cream or paste-like consistency.More preferably the bleach powder comprises about 2-5% and, mostpreferably, about 2-3% de-dusting agent by weight of the total bleachpowder.

The substantially dust-free bleach powders also comprise 1-5%,preferably 2-4% and more preferably 3% cosmetic-grade powdered PTFE byweight. Such powdered PTFE are micropowders (or waxes) known in the artthat have a lower molecular weight than that of normal PTFE, whileretaining very low solubility. (See Concise Encyclopedia of PolymerScience and Engineering, John Wiley & Sons, 1990, pp. 1167-1170,incorporated herein by reference). A preferred PTFE powder is thecosmetic-grade FluoroPURE 103C PTFE powder of Shamrock Technologies,Inc., Newark, N.J. 07114, which has an average particle size of 5μ.FluoroPURE 103C is supplied as a white powder, which is preferred foraesthetic reasons. The FluoroPURE powder is usable for powder make-upformulas, providing lubricating properties. Other sources of powderedPTFE include, inter alia, DuPont (Teflone®) and ICI (Fluron), with suchPTFE powders having similar particle size and characteristics as theabove-mentioned Shamrock product.

The substantially dust-free bleach powders preferably also contain abase including, inter alia, amine alkali compounds such astrishydroxyalkylamines, e.g., trishydroxyethylamine, guanidium carbonateor guanidium borate. Other suitable bases include alkaline silicates,such as sodium silicate or metasilicates, such as sodium metasilicate.

Preferably, ammonium sulfate or an ammonium halide compound, such asammonium chloride, or diammonium phosphate, or mixtures thereof isutilized as an ammonia source in the present bleach power. Suchcompounds are preferable to ammonium persulfate used in conventionalbleaches as an ammonia source because these compounds impart a lesserodor than ammonium persulfate. Most preferably, the ammonia source is amixture of ammonium chloride and ammonium sulfate in the dust-freebleach powders comprising PTFE (see Tables 1 and 2).

The substantially dust-free bleach powder of the invention may alsocontain one or more powdered hair conditioning agents, which cansubstantially improve the feel of hair treated with the bleachingcomposition after mixing with hydrogen peroxide. Such conditioningagents include any non-reactive polymeric material known in the art.Preferred conditioning agents include inter alia, anionic, cationic,nonionic or amphoteric conditioners.

Preferred cationic conditioners include, inter alia, polymericquaternized amine polymers with a molecular weight range of 50 kDa.Specific preferred quaternized amine polymers include MERQUAT 280, madeby the Calgon Corporation, also known as Polyquaternium-22, which is acopolymer of dimethyl diallyl ammonium chloride and acrylic acid;Polymer JR, made by the Union Carbide Corporation, also known asPolyquaternium-10, which is a polymeric quaternary ammonium salt ofhydroxyethyl cellulose reacted with a trimethyl ammonium substitutedepoxide; MERQUAT 2200, also known as Polyquaternium-7, which is apolymeric quaternary ammonium salt consisting of acrylamide and dimethyldiallyl ammonium chloride monomers; and Guar hydroxypropyltrimoniumchloride, which is a quaternary ammonium derivative of hydroxypropylGuar (gum).

Preferred anionic conditioners include, inter alia, sulfonated,carboxylated and nitro-oxide derivatives of cationic polymers, e.g.,such as pyrrolidone carboxylic acid (PCA), marketed as Ajdew by theAjinomoto Company, U.S.A., Inc.

Preferred amphoteric conditioners include chitosan and succinamide.

Preferred nonionic conditioners include monomeric and polymericcompounds such as Poloxamar 407, which is a polyoxyethylene,polyoxypropylene block polymer.

Preferably, the amount of conditioner in the substantially dust-freebleach powder of the invention is about 1%-5% by weight of the bleachpowder.

In further preferred embodiments of the invention, thickeners may alsobe added to the hair bleach powder. Hydroxyethylcellulose is a preferredtype of hydroxyalkylated cellulose thickener. In one preferredembodiment, hydroxyethyl cellulose is used in a proportion that is about3-5% by weight of the total bleach powder. Preferred thickeners alsoinclude polymeric methyl vinyl ether/malic anhydride copolymer,cross-linked by 1,9 decadiene ("PVM/MA decadiene crosspolymer").

The substantially dust-free bleach powder may also contain desiccants,such as silica. Preferably, silica is added to the bleach powder in anamount comprising about 1-3% by weight of the total bleach powder.

Surfactants, chelating agents and their salts may also be added to thesubstantially dust-free bleach powder, in an amount 0.01-2% by weight ofthe total bleach powder.

A representative substantially dust-free bleach powder according to thepresent invention may be prepared as shown in Table 1.

                  TABLE 1                                                         ______________________________________                                        MATERIAL        WEIGHT PERCENT                                                ______________________________________                                        Potassium Persulfate                                                                          30˜50                                                   Sodium Silicate 10˜25                                                   Sodium Persulfate                                                                              5˜15                                                   Sodium Metasilicate                                                                            5˜10                                                   Sodium Stearate 3˜5                                                     Silica          1˜3                                                     Ammonium Chloride                                                                             3˜5                                                     Ammonium Sulfate                                                                              1˜3                                                     Hydroxyethylcellulose                                                                         3˜5                                                     Polytetrafluoroethylene                                                                       1˜5                                                     (PTFE)                                                                        De-dusting solvent                                                                            2˜3                                                     Ethylene diamine                                                                               ˜1                                                     tetraacetic acid (EDTA)                                                       Fragrance        ˜1                                                     PVM/MA Decadiene                                                                               ˜1                                                     Crosspolymer                                                                  Polyquaternium-22                                                                             1˜5                                                     ______________________________________                                    

Preferably, the de-dusting agent is applied to the bleach powder by aspraying process.

The present invention is further described by way of the followingspecific examples. These examples are intended to be representative ofthe invention and are not in any way intended to limit its scope.

EXAMPLE 1 The Substantially Dust-Free Bleach Powders Produce ActivatedBleaching Compositions with Superior Thixotropy Properties.

The thixotropy of several activated bleaching compositions was compared.The activated bleaching compositions were made by mixing the bleachpowders designated A-G in Table 2 with aqueous H₂ O₂. Powders A, B andD, upon addition of an oil, i.e., mineral oil, represent prior artcommercial products. Powders E and F are powders prepared according tothe present invention, that do not contain PTFE. Powder G is a powder ofthe present invention containing PTFE.

                  TABLE 2                                                         ______________________________________                                        BLEACH POWDERS                                                                A   B     C     D   E   F   G   INGREDIENTS                                   ______________________________________                                            X     X         X   X   X   Ammonium Chloride                             X               X               Ammonium Persulfate                                                       X   Ammonium Sulfate                                  X                           Calcium Stearate                                                  X       X   Diisopropyl Adipate                                                   X       Dimethyl Isosorbide                               X                           Dioctyl Sodium Sulfosuccinate                                 X               Disodium EDTA                                     X     X         X   X   X   EDTA                                          X         X     X   X   X   X   Fragrance                                         X                           Guar Gum                                          X                           Hydrated Silica                               X         X         X   X   X   Hydroxyethylcellulose                                   X                     Isoeicosane                                       X           X               Magnesium Carbonate                               X                           Magnesium Oxide                                               X               Methylcellulose                               X                               Pentetic Acid                                                     X   X   X   Polyquaternium-22                                                         X   Polytetrafluoroethylene (PTFE)                X   X     X     X   X   X   X   Potassium Persulfate                                          X               PVP                                           X         X         X   X       PVM/MA/Decadiene Crosspolymer                     X                           PVP/VA Copolymer                              X   X     X     X   X   X   X   Silica                                            X                           Sodium Benzoate                               X   X     X         X   X   X   Sodium Metasilicate                           X   X     X         X   X   X   Sodium Persulfate                             X         X     X   X   X   X   Sodium Silicate                               X         X         X   X   X   Sodium Stearate                                   X                           Titanium Dioxide                                  X                           Ultramarine Blue                              ______________________________________                                    

For purposes of comparison, each of the bleach powders was mixed withaqueous hydrogen peroxide to form an activated bleach composition. Asshown below, the thixotropy values of each of the activated bleachcompositions was evaluated in terms of sheer. Sheer is determined fromthe ratio of two separately determined viscosity values, obtained by useof a heliopath spindle viscometer made by the Brookfield Company.

Viscosity measurements using the viscometer were obtained at a speed of2.5 rpm for 30 seconds using two differently sized spindles, designatedT-A and T-D. Each of the bleach compositions was placed in a beaker andpositioned under the viscometer. The spindles were then placed on thesurface of the sample, and their passage through the sample wasevaluated for 30 seconds. T-A and T-D values were expressed by theviscometer as Centipoise or cps units. The determined thixotropy valuesare expressed as the ratio of T-A/T-D. Lower values of T-A/T-D indicatesuperior thixotropy, that is, the product maintains its viscosity evenunder the sheer of application. Values >5 indicate that the activatedbleach composition will tend to fall apart under sheer. Such mixturesare paste-like, and thus are difficult to apply smoothly and evenly tohair.

Thixotropy values obtained for the different activated bleachcompositions are shown in Table 3. The activated bleach compositionsprepared using the substantially dust-free bleach powders of the presentinvention, represented by Powder E (containing an alkyl ester compound,e.g. diisopropyl adipate, see Table 2), and Powder F (containing ancyclic ether compound, e.g. dimethyl isosorbide, see Table 2), each hada T-A/T-D ratio of 0.7. Powder G, which contains powdered PTFE anddiisopropyl adipate (see Table 2) had a T-A/T-D ratio of 0.6. These lowvalues for Powders E, F and G indicate a desirable thixotropy. Theseactivated bleach compositions made with Powders E, F and G do not haveany added surfactants. In contrast, Powder A (which does not contain anyde-dusting agent) when assayed as is, or with 10% w/w mineral oil added,showed T-A/T-D ratios of 5.5 and 5.6, respectively, indicating poorthixotropy. It was necessary to add a surfactant to an admixture ofPowder A and 10% mineral oil in order to achieve a desirable thixotropy.See, Table 3.

Therefore, the comparative tests show that bleach compositions made withthe substantially dust-free bleach powders of the present invention havesuperior thixotropy properties compared with conventional bleachpowders. Specifically, compositions made with powders E and F exhibitedsuperior thixotropy over compositions prepared with de-dusting agentssuch as the oils and waxes known in the art.

                  TABLE 3                                                         ______________________________________                                        BLEND        T-A Spindle T-D Spindle                                                                             T-A/T-D                                    ______________________________________                                        Powder A     196,000 cps 35,400 cps                                                                              5.5                                        Powder B     160,000 cps 21,000 cps                                                                              7.5                                        Powder A +                                                                    10% W/W Mineral                                                                            180,000 cps 32,000 cps                                                                              5.6                                        Oil                                                                           Powder A +   33,600 cps  29,000 cps                                                                              1.1                                        10% Mineral Oil                                                               + 2% W/W                                                                      Surfactants                                                                   Powder C     40,800 cps  37,000 cps                                                                              1.1                                        Powder D     80,000 cps  240,000 cps                                                                             0.3                                        Powder E     14,800 cps  20,800 cps                                                                              0.7                                        Powder F     20,020 cps  28,800 cps                                                                              0.7                                        Powder G     28,800 cps  46,800 cps                                                                              0.6                                        ______________________________________                                    

EXAMPLE 2 The Substantially Dust-Free Hair Bleach Powders of theInvention are Resistant to Decomposition.

The stability of the bleach powders of the present invention againstdecomposition was determined by their ability to resist loss of oxygenreleasing power. Specifically, experiments were performed to determinethe amount of oxygen that is released under conditions of 95% constanthumidity within a 3-day period.

The active oxygen in the persulfate component was obtained bycalculating the amount of reducible persulfate salt in the bleachpowder. This is obtained by reducing the bleach powder with ferroussulfate, and calculating the amount of excess ferrous sulfate producedin the reaction by titration with potassium permanganate. The amount ofreducible persulfate salt is inversely proportional to the amount ofexcess ferrous sulfate, and can be calculated from the titration values.The percent values of activity represent the fraction of reduciblepersulfate in the total bleach powder, i.e. an initial activity of ˜3%corresponds to the total amount of reducible persulfate salt present inthe total bleach powder, i.e., ˜3% by weight. The loss of activity isthe difference between the amount, in percent, of oxygen released on day0 and that on day 3.

Table 4 shows the percent of oxygen released from the powders after day0 and day 3 of exposure to 95% relative humidity. The substantiallydust-free bleach powders of the invention, containing either diisopropyladipate, (Powder E of Table 2) or dimethyl isosorbide, (Powder F ofTable 2), showed substantially low loss, i.e. ˜0.2%, of activity after a3-day exposure to 95% constant humidity despite an overall ˜33% gain inweight due to absorption of atmospheric moisture.

                  TABLE 4                                                         ______________________________________                                                       POWDER E                                                                              POWDER F                                               ______________________________________                                        95% RH/wt gain (3 days)                                                                        33.33%    33.42%                                             95% RH/initial activity                                                                        3.18%     3.15%                                              95% RH/3 days activity                                                                         2.98%     2.96%                                              Loss of activity 0.2%      0.19%                                              ______________________________________                                         RH = relative humidity                                                   

EXAMPLE 3

The Substantially Dust-Free Bleach Powders of the Invention have a HighIgnition Temperature

The effect of the cyclic ether or alkylated ester de-dusting agents onthe ignition temperature of the bleach powders was determined. Theignition temperature was obtained by heating the bleach powder on ahot-plate and noting the temperature at which charring occurred. Asshown in Table 5, Powder A (of Table 2), which does not contain ade-dusting agent, had an ignition temperature of 170° C. Powder E(containing dimethyl isosorbide) and Powder F (containing diisopropyladipate) had considerably higher ignition temperatures, e.g., 190° and195°, respectively. It is an advantage for bleach powders to have highignition temperatures to eliminate the possibility of fires orexplosions during use or transport.

                  TABLE 5                                                         ______________________________________                                        Powder     Ignition Temperature °C.                                    ______________________________________                                        A          170                                                                E          190                                                                F          195                                                                ______________________________________                                    

EXAMPLE 4

Hair Bleached by the Activated Bleach Compositions of the Invention hasSuperior Combability.

Combability assays performed on hair samples bleached by the activatedbleach composition prepared using the substantially dust-free powderbleach of the invention showed reduced resistance of the hair to forcesexerted during combing.

The resistance to movement of a comb through the hair was measured in anInstron tensile test using the Instron instrument as known in the art.In this method, pneumatic pressure is applied to pull combs at a givenspeed through hair swatch samples attached to the Instron. Theresistance to movement of the comb is evaluated as (1) the forcerequired to pull the comb through the hair, expressed by the Instron asload at a maximum load, and (2) as the work done by the machine in whichthe comb is pulled through the hair, expressed by the Instron as energyat break point. Lower resistance indicates superior and desirableCombability.

For the assay, hair swatches were bleached for 45 minutes at roomtemperature and rinsed thoroughly. They were then dipped in deionizedwater, and the excess water was gently squeezed out. Then the swatcheswere slightly detangled with a fine tooth comb and clamped from the toponto the pneumatic air grip of the Instron. Two combs were placed in theInstron opposing one another such that the hair to be tested was evenlydistributed between them and the upper comb was 1.5 in. from the loweredges of the clamp. The Instron was set to pull the combs through theswatch and to the end of the swatch, at a speed of 5 in/min. The forceand work expended during this time was expressed by the Instron asdescribed above. The final readings were calculated from a mean of tensimilar and independent combability assays.

The resistance values obtained for hair bleached by the differentactivated bleach compositions are shown in Table 6. The resistancevalues of hair bleached by activated bleach compositions prepared usingPowder E and Powder F (containing the de-dusting agents of the inventionand a conditioner, e.g., Polyquaternium-22) have a load at maximum loadvalue of 53.73 gms and 36.44 gms, respectively. These values indicatedesirable combability. In contrast, activated bleach compositionsprepared using Powder D (see Table 2) which does not contain anyde-dusting component or a conditioner, has a load at maximum load valueof 336.1 gms, indicating undesirable combability.

Similarly, the energy at break point values of hair bleached byactivated bleach compositions using Powder E and Powder F are low, i.e.,134.7 gms/in. and 87.02 gms/in., respectively. In contrast, the energyat break point values using the composition containing Powder D is 1306gms/in. Thus, hair bleached by bleach compositions prepared using PowderE and Powder F, which contain the de-dusting agents of the invention anda conditioner, have substantially superior combability.

                  TABLE 6                                                         ______________________________________                                                                   ENERGY AT                                          ACTIVATED BLEACH                                                                            LOAD AT      BREAK POINT                                        COMPOSITION   MAX. LOAD (gm)                                                                             (gm/in.)                                           ______________________________________                                        Powder D      336.1        1306                                               Powder E      53.73        134.7                                              Powder F      36.44        87.02                                              ______________________________________                                    

EXAMPLE 5

Bleach Compositions Prepared with PTFE-Containing Bleach Powder haveSuperior Properties

Salon testing of bleach compositions prepared with Powder G (Table 2)and a prior art bleach, Powder C (Table 2) was carried out in Redken'sTesting Laboratories by licensed cosmetologists who are trained inevaluating hair and the effects of bleach compositions on the hair. Inparticular compositions were tested for off-scalp applicability for usein frosting and foil weaving application.

The test bleach powder (G) and the control bleach powder (C) were eachmixed with an emulsion peroxide, Redken's Pro-Oxide 20 volume peroxide.Various parameters, including inter alia, ease of mixing; viscosity;ease of application; rinsability; pre shampoo wet combing, haircondition and shine; post shampoo wet combing, wet feel, hair conditionand shine, were compared and graded for the test bleach composition andthe control. A grading system of 1-5, with 1 being the poorest value and5 being the best value was used. The results of the test are set forthin Table 7 below.

                                      TABLE 7                                     __________________________________________________________________________                     Test            Control                                                       Std. Dev.                                                                           Confidence                                                                              Std. Dev.                                                                           Confidence                             Measured Parameter                                                                         Average                                                                           (Powder G)                                                                          Level Average                                                                           (Powder C)                                                                          Level                                  __________________________________________________________________________    Mixing Ease  3.500                                                                             0.577 7.336 3.000                                                                             0.816 10.374                                 Viscosity    3.500                                                                             0.577 7.336 3.250                                                                             0.500 6.353                                  Ease of Application                                                                        3.500                                                                             0.577 7.336 3.250                                                                             0.500 6.353                                  Puffing in the Bowl                                                                        4.250                                                                             0.500 6.353 4.250                                                                             0.500 6.353                                  Puffing in the foils                                                                       4.250                                                                             0.957 12.165                                                                              4.750                                                                             0.500 6.353                                  Rinsability  3.000                                                                             0.000 0.000 3.250                                                                             0.500 6.353                                  Pre Shampoo Wet Combing                                                                    3.500                                                                             0.577 7.336 3.250                                                                             0.500 6.353                                  Pre Shampoo Hair Condition                                                                 3.250                                                                             0.500 6.353 3.000                                                                             0.000 0.000                                  Pre Shampoo Shine                                                                          3.000                                                                             0.000 0.000 3.000                                                                             0.000 0.000                                  Wet Combing  4.750                                                                             0.500 6.353 4.750                                                                             0.500 6.353                                  Wet Feel     3.250                                                                             0.500 6.353 3.250                                                                             0.500 6.353                                  Hair Condition                                                                             3.250                                                                             0.500 6.353 3.250                                                                             0.500 6.353                                  Shine        3.250                                                                             0.500 6.353 3.250                                                                             0.500 6.353                                  __________________________________________________________________________

As can be seen from Table 7, all measured parameters using the bleachcomposition made from Powder G were equal to or better than compositionsmade from Powder C.

Also, the salon results indicated that following a similar applicationtime, superior hair lightening was obtained with Powder G (data notshown).

The above examples are illustrative of the invention and are not meantin any way to limit the scope of the present invention.

We claim:
 1. A substantially dust-free bleach powder, whichcomprises:(a) a plurality of particles which comprise a peroxygenatedsalt, (b) a substantially hydrophilic de-dusting agent selected from thegroup consisting of diisopropyl adipate, diisopropyl sebacate,diisopropyl oxalate dimethyl isosorbide, diisopropyl isosorbide, andγ-butyrolactone in an amount that is less than about 10% by weight ofthe bleach powder, wherein the de-dusting agent coats the particles toprevent dust formation, and (c) powdered polytetrafluoroethylene in anamount of about 1-5% by weight of the bleach powder.
 2. The bleachpowder according to claim 1 wherein the bleach powder further comprisesa base.
 3. The bleach powder according to claim 1, wherein thede-dusting agent is present in an amount of about 2 to 5% by weight ofthe bleach powder.
 4. The bleach powder according to claim 1, whereinthe de-dusting agent is present in an amount of about 2-3% by weight ofthe bleach powder.
 5. The bleach powder according to claim 1, whereinthe polytetrafluoroethylene is present in an amount of about 2-4% byweight of the bleach powder.
 6. The bleach powder according to claim 1,wherein the powdered polytetrafluoroethylene is present in an amount ofabout 3% by weight of the bleach powder.
 7. The bleach powder accordingto claim 1, wherein the peroxygenated salt is selected from the groupconsisting of water soluble salts of persulfates, percarbonates,perborates, and metasilicates.
 8. The bleach powder according to claim 7wherein the peroxygenated salt is selected from the group consisting ofsodium persulfate and potassium persulfate.
 9. The bleach powderaccording to claim 2, wherein the base is selected from the groupconsisting of amine alkali compounds, alkaline silicates and alkalinemetasilicates.
 10. The bleach powder according to claim 9, wherein theamine alkali is selected from the group consisting oftrishydroxyalkylamines, guanidinium carbonate and guanidinium borate.11. The bleach powder according to claim 9, wherein the alkalinesilicate is sodium silicate.
 12. The bleach powder according to claim 9,wherein the alkaline metasilicate is sodium metasilicate.
 13. The bleachaccording to claim 9, wherein the trishydroxyalkylamine istrishydroxyethylamine.
 14. The bleach powder according to claim 1,wherein the bleach powder further comprises a source of ammonia selectedfrom the group consisting of ammonium halides, diammonium phosphate,ammonium sulfate and mixtures thereof.
 15. The bleach powder accordingto claim 14, wherein the ammonium halide is ammonium chloride.
 16. Thebleach powder according to claim 14, wherein the ammonia source is amixture of ammonium chloride and ammonium sulfate.
 17. The bleach powderaccording to claim 1, further comprising at least one hair conditioningagent.
 18. The bleach powder according to claim 17, wherein the hairconditioning agent is a monomeric or polymeric compound selected fromthe group consisting of cationic, anionic, amphoteric and non-ioniccompounds.
 19. The bleach powder according to claim 18, wherein the hairconditioning agent is polyquaternium-22.
 20. The bleach powder accordingto claim 1, further comprising at least one thickener.
 21. The bleachpowder according to claim 20, wherein the thickener ishydroxyethylcellulose.
 22. The bleach powder according to claim 1,further comprising at least one desiccant.
 23. The bleach powderaccording to claim 22, wherein the desiccant is silica.
 24. Asubstantially dust-free bleach powder, which consists essentially of:(a)a plurality of particles which comprise a peroxygenated salt; (b) asubstantially hydrophilic de-dusting agent selected from the groupconsisting of diisopropyl adipate, diisopropyl sebacate, diisopropyloxalate dimethyl isosorbide, diisopropyl isosorbide, andγ-butyrolactone, wherein the de-dusting agent coats the particles toprevent dust formation; (c) powdered polytetrafluoroethylene; (d) abase; (e) an ammonia source; (f) a hair conditioning agent; (g) athickener; and (h) a desiccant.
 25. The bleach powder according to claim24, wherein the de-dusting agent is present in an amount less than about10% by weight of the bleach powder.
 26. The bleach powder according toclaim 24, wherein the de-dusting agent is present in an amount of fromabout 2 to 50% by weight of the bleach powder.
 27. The bleach powderaccording to claim 24, wherein the de-dusting agent is present in anamount of from about 2 to 3% by weight of the bleach powder.
 28. Thebleach powder according to claim 24, wherein the powderedpolytetrafluoroethylene is present in an amount of about 1-5% by weightof the bleach powder.
 29. The bleach powder according to claim 24,wherein the powdered polytetrafluoroethylene is present in an amount ofabout 2-4% by weight of the bleach powder.
 30. The bleach powderaccording to claim 24, wherein the powdered polytetrafluoroethylene ispresent in an amount of about 3% by weight of the bleach powder.
 31. Thebleach powder according to claim 24, wherein the ammonia source is amixture of ammonium chloride and ammonium sulfate.